The present invention concerns in particular the mounting of clothing on flats of a card.
1. Previous Patent Application/Field of Application
The present invention is particularly, but not exclusively, aimed at applications in combination with a "small card", i.e. a card the main drum of which has a relatively small diameter. An example of a card of such type is described in patent application EP 98 810088.9 filed Feb. 19, 1998 (Equivalent--U.S. Ser. No. 09/028,425 dated Feb. 24, 1998). The contents of said previous applications are herewith incorporated into the present description.
The present invention also presents particular advantages in connection with a "wide card", i.e. a card the working width of which exceeds 1000 mm. A card of such type also is described in the preceding applications, other wide cards also being known, e.g. the "Super Card" which was offered by the Schubert & Salzer Company. A flat for a machine of this type is shown in U.S. Pat. No. 4,827,573.
Furthermore use of the present invention in conventional cards and roller cards is not excluded even if the present invention was not conceived specifically for such applications. The application in conventional cards comprises the application in so-called fixed flat cards equipped e.g. with fixed flats according to EP-B-431 482.
2. State of the Art
Basic studies concerning the mounting of clothing on revolving flat cards have been undertaken by the Institut fur Textil- und Verfahrenstechnik Denkendorf (Institute for Textile and Process Engineering at Denkendorf) as can be seen especially from the literature cited in the following:
(i) Melliand Textilberichte, October 1885, pages 707 ff., and PA0 (ii) textil praxis international, September 1994, pages 551 ff. PA0 (i) the density of the clothing, or of the points respectively, in the heel zone in some cases is chosen higher than the point density in the front zone of the strip (which is the case for the two strips 17, 18 shown in the FIG. 4) The actual values of the point density should be chosen as a function of the main drum clothing characteristics, the rotational speed of the main drum and of the material to be processed (compare the above mentioned article in Melliand Textilberichte), PA0 (ii) the heel zone in most cases is provided with a so-called "heelgrinding" finish in which the clothing plane BF of the points in the heel zone is arranged at an angle with respect to the above mentioned clothing plane BE of the points in the front zone (which applies only to the strip 18 shown in the FIG. 4). PA0 both have points in respective planes each of which extends parallel to the contacting surface, PA0 both have points in respective planes each of which is arranged at an angle (at the same/different angles) with respect to the contacting surface, or PA0 one of the clothing planes can be arranged parallel to, and the other one at an angle with respect to, the contacting surface. PA0 the wire thickness, PA0 the point arrangement pattern. PA0 the freshly supplied (not yet fully opened) fibre material first meets the front wires which thus are subject to the highest load. PA0 Application of coarser wires in the front zone exerts a lesser influence on the achievable technological result than a corresponding change in the heel zone. PA0 (i) Each group can be provided with a different wire thickness, and PA0 (ii) Within each group different wire thicknesses can be provided.
Furthermore, since 1954 it is known (DE-Gbm-16 94 956) that formation of "carding lines" by subdividing the clothing points into groups can present advantages under certain conditions. The latter proposal is not widely used in practice, or rather has been overlooked in the meantime in further development of high performance cards.
Also the proposal described in the DE-Gbm 1733250 of using a flat the clothing of which is formed "by wire points of different diameter wires" has become obsolete.